The olefin hydration reaction is an important reaction for the production of alcohols, and is utilized industrially. Isopropyl alcohol and 2-butanol are produced by various methods utilizing the hydration of propylene or n-butene (Non-Patent Document 1 and Non-Patent Document 2). The method currently employed in the plants in the world is the method comprising reacting propylene or n-butene with sulfuric acid and hydrolyzing the resulting sulfate ester (indirect hydration). This method has problems, however; for example, byproduct formation is significant, sulfuric acid is required in large amounts, and also has such problems as apparatus corrosion by sulfuric acid, recycling of sulfuric acid and waste liquid treatment. Also available are methods using various catalysts in direct hydration. For example, there are methods using an ion exchange resin as a catalyst and methods using, as a catalyst, a solid acid comprising phosphoric acid or a like mineral acid supported on a carrier. However, the ion exchange group (sulfonic acid group) may be eliminated by hydrolysis or the acid supported on carrier may be detached from the carrier during reaction to cause a decrease in activity and/or apparatus corrosion. It becomes necessary to take measures against such cases. And more, in the case of an ion exchange resin catalyst, there are also such problems, for example, that the catalyst is expensive and that the reaction temperature is restricted due to the poor heat resistance property of the resin. Also known are the methods which use a homogeneous molybdenum- or tungsten-based polyanion solution (aqueous heteropolyacid solution) as a catalyst; but they require high-temperature and high-pressure reaction conditions, however. In any case, in olefin hydration reaction method, the use of an acid catalyst is essential and each method has problems due to catalyst properties.
On the other hand, various acid catalysts are used in various reactions in industrial processes. From point of view of catalyst performance, energy saving and cost, catalysts excellent in these points are required. Solid acid catalysts, in particular, are promising since they will make it possible to simplify processes. Thus, various such catalysts have been developed. Among them, recently developed carbon-based solid acids obtained by carbonization and sulfonation of organic matters have attracted attention and applications thereof have been attempted (Non-Patent Document 3, Non-Patent Document 5, Patent Document 1 and Patent Document 2). As regards the olefin hydration reaction, an example is known in which 2,3-dimethyl-2-butene was subjected to the reaction at a low temperature (70° C.) but nothing is known about the hydration reaction of lower olefins differing in reactivity therefrom (Non-Patent Document 4).
Non-Patent Document 1: Shokubai (Catalysts & Catalysis), Vol. 18, No. 6, pp. 180-184, 1976
Non-Patent Document 2: Sekiyu Gakkaishi (Journal of the Japan Petroleum Institute), Vol. 34, No. 3, pp. 201-209, 1991
Non-Patent Document 3: Atushi Takagaki, Junko Nomura, Michikazu Hara, Shigenobu Hayashi and Kazunari Domen: “Carbon-based strong solid acids: synthesis conditions and catalysis”, 85th Annual Meeting (Spring) of the Chemical Society of Japan (2005), 2B5-43
Non-Patent Document 4: Angew. Chem. Int. Ed., 43, 2955-2958 (2004)
Non-Patent Document 5: Nature, 438, 10, p. 178, November, 2005
Patent Document 1: Japanese Patent (Laid-Open) Publication No. 2004-238311
Patent Document 2: International Patent Publication No. WO2005/029508